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If sinA + sin2A = 1 then what is the value of cos2A + cos4A?
If sinA + sin2A = 1 then what is the value of cos2A + cos4A?
1). ½
2). 1
3). 2
4). 3
This Question has 2 answers.
Given,
sinA + sin2A = 1
⇒ sinA = 1 – sin2A = cos2A ----(1) (? sin2θ + cos2θ = 1)
Squaring on both sides
sin2A = cos4A ----(2)
Substitute (1) and (2) in the given expression.
cos2A + cos4A = sinA + sin2A = 1
∴ cos2A + cos4A = 1
Given,
sinA + sin2A = 1
⇒ sinA = 1 – sin2A = cos2A ----(1) (? sin2θ + cos2θ = 1)
Squaring on both sides
sin2A = cos4A ----(2)
Substitute (1) and (2) in the given expression.
cos2A + cos4A = sinA + sin2A = 1
∴ cos2A + cos4A = 1
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